There are currently at least four commercial systems being used to space dye yarns used to fabricate multi-color carpets. These four systems may be divided into two basic classifications known as continuous systems and batch systems.
One of the two continuous systems used in the textile industry is the knit-de-knit space dyeing process which is generally described in U.S. Pat. No. 3,012,303, issued Dec. 12, 1961, to Ralph Whitaker. This process consists of six basic steps. The yarn is first knitted into a fabric after which a stripe or other pattern is printed on the knitted fabric. The color is set by steam color fixation of the knitted fabric which is then scoured to remove gums and excess dyes. After the knitted fabric is dried, the final step includes de-knitting of the knitted fabric to a cone of yarn.
The other of the continuous systems is generally known as warp printing. It also involves six basic steps including preparation of warp sheets (creeling) and thereafter application of a stripe or pattern which is printed on the warp sheet. The color is set by steam color fixation of the warp sheet which is then scoured to remove gums and excess dyes. After the warp sheet is dried, it is split and the yarns rewound onto cones.
Both types of the continuous systems suffer from similar disadvantages in that they require high levels of water consumption and expensive water treatment to remove pollutants. Costs of operation are high due to wasted energy in atmospheric steaming, continuous drying and high labor requirements.
The two batch systems in commercial use are injection dyeing and skein dyeing. Injection dyeing processes have been known for over a half of a century. Still, injection dyeing accounts for only a small portion of the textile yarn being dyed into multi-colors. A typical process for injection dyeing is described in U.S. Pat. No. 1,726,984 to Louis Hasbrouck, dated Sept. 3, 1929. Another injection dyeing process is disclosed in U.S. Pat. No. 3,120,422, dated Feb. 4, 1964. Both of these patents cover dyeing of one cone at a time with the use of hypodermic needles inserted into the cone of yarn to apply the dyes. As hereinbefore noted, injection dyeing processes have not found a great deal of commercial acceptance.
In the other of the batch systems used in the textile industry, the yarn is first unwound from its cones or bobbins to skeins which are loaded into the vat of a dye machine. The skeins are totally submerged in a dye bath and a base color is applied. The skeins are then partially raised out of the dye bath, and may further be rotated depending on the design of the machine and a second color is applied to the portion of the yarn submerged in the dye bath. This step is repeated for each additional color desired, after which the skeins are removed from the dye machine and put into a centrifugal extractor to remove the excess water. The skeins are then dried in an oven drier after which the skein dyed yarn is rewound on cones for further processing.
A typical apparatus for space dyeing of skeins by total submersion and application of a base color and thereafter selective withdrawal or raising of the skeins to apply additional colors to the partially immersed yarn was placed in commercial production in late 1971 by James H. Eakes and is described and illustrated in his application Ser. No. 480,026, filed June 17, 1974, now abandoned. Such apparatus for producing space dyed skeins of yarns is also described and illustrated in O'Mahony et al. U.S. Pat. Nos. 3,926,547 and 3,986,375.
For example, the supercarriers of skeins in such apparatus must be so constructed as to support the greatly increased weight of the yarn following immersion. Generally, a compromise must be accepted by operation at less than full capacity of the apparatus to prevent bending of the cantilever yarn supporting tubes. Additional problems experienced with skein dyeing are: maintaining the liquor ratio constant, high water consumption and high energy requirements. Some of the latter problems are overcome by the vat dyeing process described in my copending application Ser. No. 846,988 filed Oct. 31, 1977 and entitled Method and Apparatus For Randomly Coloring Textile Yarns In A Batch System.
Multi-color or space dyed yarn has experienced a high degree of popularity among carpet manufacturers who continually strive for materials which enable them to meet the demands for continuous changes in styling and an objective of this invention is to provide a much more economical, practical and convenient method and apparatus for the space dyeing of yarns.
More particularly, it is an objective of the invention to provide a continuous process for space dyeing yarns which economizes on the consumption of water and energy while utilizing a comparatively simple and inexpensive apparatus.
Another objective is to provide a continuous process for space dyeing yarns which avoids the drawbacks of the prior art knit-de-knit, warp printing processes and vat dyeing processes.
Other objectives and advantages of the invention will become apparent during the course of the following description.